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Patented Mar. l4, I899.

u. a. WARTH. ELECTRICAL DEVICE INVOLVING HERMETICALLY INCASEDCONDUCTORS.

(Application filed Dec. 7, 1597.

(No Model.)

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R TQQTZVMQ wyne ssaivz m l 0% m6 UNITED STATES PATENT OFFICE.

NATHANIEL G. \VARTH, OF INDIANAPOLIS, INDIANA.

ELECTRICAL DEVICE iNVOLVlNG HE RMETICALLY-INCASED CONDUCTO RS.

SPECIFICATION forming part of Letters Patent No. 621,001, dated March14, 1899.

Application filed December '7, 1897.

T (LZZ whom it may concern:

Be it known that I, NATHANIEL G. WARTH, a citizen of the United States,residing at In dianapolis, in thecounty of Marion and State of Indiana,have invented a certain new and useful Electrical. Device InvolvingHermetically-Iucased Conductors, of which the following is aspecification.

My invention relates to electrical devices involving in theirconstruction one or more electrically-insulated conductors orconductor-sections and depending for a high degree of efficiency largelyupon the possession by their insulating media or dielectrics of a lowspecific inductive capacity or a high specific resistance or a highdielectric strength or upon two or all three of thesecharacteristicssuch devices, for instance, as induction-coils,converters, condensers, telegraph and telephone cables, and the like.

Prominent objects of my invention are as follows, to wit: to reduce to aminimum the electrostatic capacity of such devices and to increase to amaximum the specific resistance and dielectric strength of theirdielectrics; to allow such reduction in electrostatic capacity andincrease in specific resistance and dielectric strength to be securedWithout necessitating an accompanying objectionable variation in thesize, form, or construction of the devices; to prevent, so far aspossible, sparking or flashing across the dielectric and also to preventthe combustion of the latter and the generation of expansive orexplosive gases; to render practically impossible the composition of thedielectric being so altered as to permit it either to maintain a sparkor support combustion; to arrange for the automatic notification ofattendants of the creation of conditions which would impair theefficiency of thedielectricand also for the automatic prevention of suchimpairment after the creation of such conditions and until theattendants have opportunity to remove, adjust, or repair the same, andto attain such results in a simple, practical, inexpensive, effective,and highly-eflicient manner.

In a device of the class specified characterized by my invention thedielectric is composed in part of air or like gas in a rarefiedcondition. As a result its specific inductive Serial No. 661,107-

capacity is reduced and its specific resistance increased, for thereason that the specific inductive capacity of rarefied air is less andthe specific resistance thereof greater than the correspondingproperties of any other known substance or materials. As a furtherresult the liability of combustion within the device is materiallyreduced by the extraction of a greater or less proportion of the oxygenwhich would otherwise support it. As a preferred arrangement therarefied air forming the dielectric is rarefied to the highest possibledegree-that is to say, so as to form thereof the nearest possibleapproximation to an absolute vacuum. In this way the spe- (No model.)

cific inductive capacity of the dielectric is re- 7 duced to an absoluteminimum and the specific resistance thereof increased to an absolutemaximum, While at the same time the dielectric strength of the same isalso increased to a maximum. In this way also the liability ofcombustion and the danger of such an alteration in the composition ofthe dielectric as to cause the same either to act as a conductor, or togenerate explosive or expansive gases, or to maintain a spark, or tosupport combustion are practically removed by reason of the substantialabsence of oxy gen from within the device.

All of the above advantages, it will be ob served, can be securedwithout objectionably increasing the size or varying the form orconstruction of the device.

In carrying out myinvention I confine the insulated conductors within animpermeable and hermetically-sealed hollow of chamberedconductor-holdersuch, for example, as the tubular metallic sheath orcasing of a telephone or telegraph cable-and then exhaust from theinterior of such hollow holder substantially all of the air lying in theotherwise unoccupied space or spaces within it and between theconductors themselves or between the same and the interior walls of theholder, or both. f

Obviously devices of the class specified now in use and involving intheir construction a mass of porous and fibrous insulation-such, forinstance, as hygroscopically insulated electric cables-can have myinvention applied to them by making them hermetically tight, if they arenot already so constructed, and then exhausting substantially all theair from within them.

In this application I show my invention applied to an electric cable,such as a telephone or telegraph cable, involving in its construction aplurality of longitudinally-disposed i11- sulated conductors and animpermeable and hermeticallysealed lead or other metallic pipe in whichthe conductors and the insula tion therefor are confined. In view of theforegoing, however, it will be readily seen that my invention can beapplied to any and all of the devices of the class specified. ThereforeI do not wish to limit myself to its application to an electric cable,but consider that it is applicable to any and all devices of the classspecified. In connection with this said cable I have shown meansforindicatinga condition of permeability of the cable-sheath, whichcondition would of course permit an impairment of the cable-dielectricbythe admission of the external atmosphere or other surrounding medium,and also means for notifying the attendant of the creation of suchcondition and for temporarily preventing the resulting impairment of thedielectric until such condition can be removed or repaired by theattendants. Such means can of course be used in connection with anydevice of the class specified.

In the accompanying drawing the figure is an electric cable embodying myinvention and an apparatus for indicating and notify- 111g attendants ofthe creation of a condition of permeability of the sheath thereof andalso for automatically preventing the impairment of the dielectric bythe admission of the external air or other surrounding medium upon thecreation of such condition,

The cable A shown comprises a plurality of longitudinally-disposcdconducting-wires a o, a mass of solid insulating material a, in whichthe conductors a a are embedded, and a metallic sheath or covering awhich incloses the conductors a a and the insulating material a. Thisinsulating material could be fibrous material, such as jute-cotton, andthis material could be either in the dry state or be treated with anywell-known insulating compound or oil to increaseits insulatingcapacity, or it could be of any well-known rubber compound or anyothersuitable insulatmg material; but as a preferred construction it isuntreated or dry fibrous material,

for such material has itself a less specific inductive capacity than theheavier materials and so gives the cable a less specific capacity thanwould be given by thelatter,other things being equal, while at the sametime it is more porous and so affords more and larger spaces which cancontain the rarefied air or like gas.

The ends of the cable can be hermetically sealed, so as to prevent theadmission of the surrounding medium into the cable-sheath and at thesame time to allow the ends of the cable-conductors to be connected upfor sertherefrom, so as to create a substantial vacvice in any suitableway. As a preferred arrangement, however, they are thus sealed by animproved cable-terminal, which is shown and claimed in Letters PatentNo. 003,069, granted and issued to me April 26, 1898. Inasmuch as saidterminal is fully illustrated and described in my said patent I shallrefer to it herein only briefly. In it the ends of the cable-conductorsa a are allowed to protrude from the end of the cable-sheath a and areconnected by suitable connections a with a plurality ofnon-hygroscopically-insulated conductors B B, which latter are suitablyconnected up for serviceas, for example, to contacts ,0 c on aswitchboard O. The protruding ends of the cable-conductors a (1,, theends of the service-wires B B,eonnected thereto, and the connections a abetween the former and the latter are then confined in an impermeable,preferably metallic, sleeve D, which is slipped a short distance overthe end of the cable-sheath a and is secured thereto by ahermetically-tight joint-as,for instance, the wiped joint I). The sleeveD is next sub stantially filled with a sealing material E, such asbeeswax or asphaltum compound in a molten condition, so that theconductor portions and connections are hermetically embedded therein andthe sealing material allowed to cool and harden, and finally the end ofthe sleeve D, which the service-conductors I3 B enter, is closedaboutthe latter at a point where the same are assembled into a compactcore, as at B. This cable-terminal can of course be used in connectionwith any form of cable and when so used possesses many decidedadvantages, as fully set forth in my other said application. As apreferred arrangement the cable end and the sleeve D are securedpermanently for serviceinan uprightor substantially vertical position,as shown in the drawing, in which case the sealing material E isprevented from oozing or running out should it become heatedsufiiciently to melt it.

The air within the interior of the cablesheath a could be substantiallyexhausted uu m in the otherwise unoccupied space thereof, in anysuitable or preferred way. In the arrangement shown it is exhausted byway of a valved exhaust-pipe F, attached to the cable-sheath a near theend of the latter and understood to be connected at a point beyond itsvalve F with a suitable exhaustpump. (Not shown in the drawing.) Afterthe air within the sheath has been sufiiciently exhausted therefrom thevalve I is closed and the exhaust-pump stopped or disconnected. Theextent to which the air has been exhausted from within the sheath, or,in other words, the degree of rarefaction of such air can be indicatedby a suitable pressure gage G, adapted to indicate a degree ofair-pressure and conveniently attached to the exhaust-pipe F between itsexhaust-valve F and its connection with the cable-sheath a ICC The handg of the gage indicates by its position the air-pressure within thesheath. Vhether or not the cable-sheath is and remains impermeable isalso indicated by the gage G. If the pointer 9 thereof remainsstationary, it indicates a condition of impermeablility of thecable-sheath; but if it moves back toward the point or figure indicatingthe normal atmospheric pressure it indicates the admission of thesurrounding medium, and consequently the permeability of such sheath. 1desirably make suitable provision for automatically notifying theattendants upon the creation of such a condition of permeability of thecable-sheath. As a simple arrangement an electric alarm II, mounted upona suitable base or support 11, and a battery J are included in anelectric circuit K, which latter is connected with the gage G in such amanner as to cause the bell II to ring when the pointer g of the gageindicates the existence of normal atmospheric or any other predeterminedpressure within the cable-sheath. The circuit K is thus connected withthe gage G by terminating one side 7; thereof at the metallic case ofthe gage and the other side K at a contact g, adapted to make connectionwith the pointer g and situated on the face or dial of the gage at thepoint indicating the normal atmospheric or other predetermined pressure.By such arrangement the movement of the pointer 9 into contact with thecontact 9 closes the circuit K, and thereby automatically causes thebell II to be rung.

As an arrangement for automatically maintaining the permanency of thecable dielectric after the creation of a condition of permanency of thecable-sheath until the attendants can obviate such condition drycompressed air is upon the creation of such condition automaticallyadmitted into the interior of the cable-sheath, so as to cause the sameto occupy the spaces and interstices previously occupied by the rarefiedair. In this way the external air or other surrounding medium isexcluded from the interior of the cable-sheath, and consequent injury tothe dielectric of the cable thus prevented, until the pressure of thedry compressed air is reduced to normal atmospheric pressure by aportion thereof escaping through the cable-sheath. However, inasmuch asimpairments to the impermeability of cable-sheaths are usually veryslight some time will elapse before such a reduction of the pressure ofthe compressed air is effected and so the attendants will haveconsiderable time in which to make repairs. As a simple and effectivearrangement the compressed air so admitted is stored preparatory toadmission in a suitable tank or reservoir L and is automaticallyadmitted into the cable-sheath a upon the impairment of the latter byway of a supply-pipe L, connected to the reservoir H and to theexhaust-pipe F at a point between the valve F of the latter and theconnection thereof with the cable-sheath a This pipe L is provided witha valve Z, which is normally closed, so as to normally prevent thecompressed air in the tank L from passingin to the interior of thecable-sheath a and is automatically opened upon the impairment of suchsheath. As a simple arrangement for thus automaticallyopening the valvel the valve-lever Z has attached to it a norm ally-suspended andautomatically-released rope or cord M, carrying a weight N, so that whenthe cord M is automatically released the Weight N draws it downward anddepresses the valve-lever Z and opens the valve Z. The

cord M is normally held in suspension by the engagement of an eye orring at on its upper end with a pin 19, which extends laterallyfrom avertically-swinging pivoted lever P, and is automatically released bythe sliding of such I eye or ring on from the pin p when the pivotedlever P is unlocked and allowed to swing downward. Thevertically-swinging lever P is locked in vertical position by apivotally-supported catch Q, pivoted to the base H and constructed atits outer end with a hook which engages the upper end of the swinginglever P and so prevents the weight N from drawing such lever downward.The pivotal catch Q normally rests in horizontal position upon the upperend of the swinging lever P when its hook is in engagement therewith. Itis automatically lifted, so as to release the lever P and thereby allowthe weight N to drop and close the valve Z, by an electromagnet R,whichis mounted on the base H and which is included in the circuit K and sois energized upon the movement of the gage-hand g into contact with thecontact-piece g. In this way the creation of a condition of permanencyof the cable-sheath will simultaneously and automatically both notifythe attendants by ringing an alarm-bell and maintain the permanency ofthe cable insulation until the im perfection in the cable-sheath can bepermanently repaired. After such repairlnent the supply of drycompressed air can be shut off and the air within the cable-sheath againexhausted.

Afterthe cable has been repaired and the air again exhausted therefromthe compressedair tank or reservoir can be recharged by way of a valvedsupply-pipe L attached to'the pipe L and understood to be connected witha suitable source of compressed air, which can be operated to till thetank. Of course, if convenient, the tank L can be omitted altogether andan operative source of compressed air connected directly to andcontrolled so as to discharge automatically into the cablesheath in themanner described in connection with the tank L.

It is obvious that where a plurality of cables are terminated at thesame point each one can be provided with a separate pressure-gage, andthese gages can be suitably mounted for inspection upon a singleswitchboard. It is also obvious that the alarm-bell andcompressed-air-supplying arrangements can be employed in connection withcables or the like containing air under pressure instead of rarefiedair. In such latter case it is only necessary to fix the contact g onthe gage-dial at the point indicating any predetermined pressure.

Having thus described my invention, what I claim as new therein, anddesire to secure by Letters Patent, is-

I. In an electric cable, an impermeable and hermetically-sealed sheathcontaining fibrous insulating material and rarefied air which latter inpart forms the dielectric for the conductors when the cable is in use.

2. The combination of a device involving in its construction one or moreinsulated conductors or conductor-sections, and an impermeable andhermetically-sealed hollow holder which incloses the conductors orconductorsections, and which contains air or like gasunder a pressureother than the normal atmospheric pressure; and means for automaticallynotifying the attendants of the impairment of the impermeability of thehollow holder, as set forth.

3. The combination of a device involving in its construction one or moreinsulated conductors or conductor-sections and an impermeable andhermetically-sealed hollow holder which incloses the conductors orconductorsections, and which contains air or like gas under a pressureother than the normal atmospheric pressure; a pressure-indicating gageconnected so as to indicate the degree of pressure within the hollowholder; and an electric circuit provided with an alarm-bell and abattery, and connected with the gage so as to cause the bell to be rungat a time when the gage indicates a predetermined pressure, as setforth.

4:. The combination of an electric cablehaving a normally im perforateand hermeticallysealed sheath containing rarefied air; a pressureindicating gage having a swinging pointer and an electric contactadapted to I make connection with the pointer and situated at a pointindicating a pressure other than the normal pressure within the sheath;and an electric circuit provided with an alarm-bell and a battery, andconnected with the gage-pointer and contact so that when the formermoves into contact with the latter the circuit is closed and the bellrung, substantially as described.

5. The combination with a device involving in its construction one ormore insulated conductors or conductor-sections, and an impermeableandhermetically-sealed hollow holder which incloses the conductors orconductorsections, and which contains air or the like under a pressureother than the normal atmospheric pressure; and'means forautomaticallypreventing the admission of the external airorothersurrounding medium upon the creation of a condition ofpermeability on the part of the hollow holder, as set forth.

6. The combination with a device involving in its construction one ormore insulated conductors or conductor-sections, and an impermeable andherm etically-sealed hollow holder containing the same and alsocontaining air under a pressure other than the normal atmosphericpressure; means for supplying dry compressed air; and means forautomatically admitting such air into the interior of the hollow holderupon the creation of a condition of permeability thereof, as set forth.

7. The combination with a hollow impermeable and hermetically-sealedconductorholder containing one or more conductors or conductor-sections,and also containing air or the like under a pressure other than thenormal atmospheric pressure; of a pressure indicating gage connectedwith the hollow holder so as to indicate the pressure therein, means forsupplying dry compressed air; a valved supply pipe extending from suchmeans to the hollow holder; a weighted cord attached to the supply-pipevalve-lever so as to depress the same and open the valve when free todescend; a pivotally-supported swinginglever having alaterally-extending arm or projection adapted to engage a ring at theend of the weighted cord, and thereby normally hold such cord insuspension a swinging catch norm ally engaging the swinging lever so asto hold the same in position to retain the lateral arm thereof and saidring in engagement; an electromagnet adapted when energized to actuatethe swinging catch in a way to disengage the same from the swin ginglever,and thereby allow the latter to swing and the weighted cord todescend and open the supply-valve; and an electric circuit including theelectromagnet and connected with the pressure-gage so as to be closedupon the indication thereby of any predetermined pressure, substantiallyas described.

8. The combination with a hollow impermeable and hermetically-sealedconductorholder containing one or more conductors or conductor-sectionsand also containing air or the like under a pressure other than thenormal atmospheric pressure; of means for antomatically notifying theattendants of the creation of a condition of permeability of the hollowholder; and means for temporarily preventing the admission of theexternal air or other surrounding medium into the holder after thecreation of such condition as set forth.

In testimony whereof I affix my signature in presence of two witnesses.

NATHANIEL G. WARTII.

\Vitnesscs:

CHAS. O. BULKLEY, L. IV. BULKLEY.

